This iconic building is from Acturus : The Curse and Loss of Divinity. Acturus was made by the same person that made Ragnarok Online
Acturus : The Curse and Loss of Divinity was published on PC during 2001 in Korea and 2003 in Japan.
There were rumor that an English version would came out but haven’t seen the light till today. The were also a group of translator working on this game, but they decided to stop as they found the game has a lot of bug and deem it not worth it.
Acturus looks and feel like it sibling, Ragnarok Online but with a RTS gameplay. Acturus building requires 3 sheets of paper and easy to make.